Hydraulic transmission for machine tools



Feb. 24, 1948. J, SNADER 2,436,406

HYDRAULIC TRANSMISSION FOR MACHINE TOOLS Original Filed Dec. 2, 193'? 6Sheets-Sheet 1 5m! CJSnaa er Feb. 24, 1948. I. J. SNADER 2,436,406

HYDRAULIC TRANSMISSION FOR MACHINE TOOLS Original Filed Dec. '2, 1937 6Sheets-Sheet 2 my zzzzi IW (ATTOIQ Q ill.

Feb. 24, 1948. sNADER 2,436,406

HYDRAULIC TRANSMISSION FOR MACHINE TOOLS Original Filed Dec. 2, 193? 6Sheets-Sheet 3 iNVENTOQ/ %$naderfwd; 60.4; 0 v- M i arrows);-

Feb. 24, 1948. I. J. SNADER HYDRAULIC TRANSIISSION FOR MACHINE TOOLSOriginal Filed Dec. 2, 193? 6 Sheets-Sheet 4 ramp, 975w Snadeh (/hmwsysFeb. 24, 1948. 1. J. SNADER 2,436,406

HYDRAULIC TRANSMISSION FOR MACHINE TOOLS Original Filed Dec. 2, 1937 6Sheets-Sheet 5 Feb. 24, 1948. 1. J. SNADER HYDRAULIC TRANSMISSION F ORMACHINE TOOLS Original Filed Dec. 2, 1957 6 Sheets-Sheet 6 ate nte F e.24,1

i 1| RAULIC TRANSMISSION FOR MACHINE TOOLS Era .ll. Snader, Detroit,Mich., assignor to Ex- Cell-O Corporation, Detroit, Mich, a corporationof Michigan Claims.

The present invention relates to improvements in hydraulic,transmissions for machine tools for performing material cuttingoperations, particularly machine tools for grinding screw threads.

' One object of the invention is to provide a new and improved threadgrinding machine having a work table translatable by a mechanical drive,a work spindle mounted thereon, and a rotary hydraulic motor foroperating said drive and said spindle in timed relation.

Further objects and advantages will become apparent as the descriptionproceeds.

Figure 1 is a front elevational view of the machine having a hydraulictransmission embodying the features of my invention.

Fig. 2 is a vertical sectional view of the headstock taken along line2-2 of Fig. 1.

Fig. 3 is a fragmentary sectional view taken along line 3-3 of Fig. 2. I

Fig. 4 is a fragmentary substantially vertical sectional view takenalong line 5-5 of Fig, 2, and illustrating the mounting and drive forthe headstock spindle.

Fig. 5 is a fragmentary horizontal broken sectional view of the worktable illustrating particularly a taper compensating mechanism. I

Fig. 6 is a fragmentary verticalsectional v'ew of the work table, andparticularly the means for supplying pressure fluid thereto.

Fig. 7 is a fragmentary vertical sectional view taken along line 'l-l ofFig. 2.

Fig. 8 is a diagrammatic representation of the hydraulic circuits forthe machine.

While the invention is susceptible of various modifications andalternative constructions. I have shown in the drawings and will hercindescribe in detail the preferred embodiment, but it is to be understoodthat I do not thereby intend to limit the invention to the specific formdisclosed, but intend to cover all modifications and alternativeconstructions falling within the spirit and scope of the invention aexpressed in the appended claims.

The present application is a division of my copending application SerialNo. 177,693, filed December 2, 1937 (Patent No. 2 251,961).

Referring more particularly to the drawings, the hydraulic transmission,constituting the exemplary embodiment of the invention, is incorporatedin amachine comprising a base I which may be of any suitable form, andwhich preferably is horizontal, with an elongated front section 2. Thetop of the base section 2 is formed with longitudinal ways on which awork carriage or table 6 is suitably mounted for reciprocation.

2 A headstock 7, having a power driven work spindle 8, is mounted on thecarriage B for movement therewith, and is pivota y adjustab e to adaptthe machine for either cylindrical or taper grinding. A tallstock 9,having a work engaging center ill in axial alignment with the spindle 9,may be adjuztably' mounted on longitudinal ways it formed on the top ofan elongated frame extension IZ of the headstock l. The top of the basealso supports a tool fixture it mounted for. cross feed and adjustment.The fixture it has a power driven spindle it which is adapted to supporta suitable grinding element or wheel it for operative engagement withthe work, and which is angularly adjustable to compensate for the leadangle of the work thread when grinding screw elements.

The Headstock One end of the headstock l is formed with a hollowupstanding spindle housing 28 formed internally with a drive compartment29 and a change gear compartment 38 separated by an intermediate walliii. The compartment 29 is closed at the front by a removable cover 32,and the compartment 30 is closed at the end by a removable cover 33. Thespindle 8 is journaled adjacent opposite ends in suitable antifrictlonbearings 3t and 35 mounted respectively in the end walls of thecompartment 29, and preferably is tubular and of the flange nose endtype. Thus, the outer or operative end of the spindle 8 is provided witha flange 36 formed with an axial loeating bore or recess 37 to mount awork fixture such as a chuck (not shown). The outer end portion of thespindle bore is tapered to form a socket 30 for a sleeve 39 into which awork center 40 may be removably inserted. An opening 48 in the cover 33for the compartment 30 and normally closed by a removable plate 62affords access to the inner end of the spindle 8 and permits insertinglong work pieces through the spindle.

Rigidly mounted within the drive compartment 29 is a motor 43 which inthe present instance is of the rotary hydraulic type. The motor 43 isconnected through step pulleys 44 and 45 and a belt 46 to a transverseworm shaft 41 journaled in antlfriction bearings 48. An idler pulley 49serves to tension the belt 56. A worm 50 on the shaft 41 meshes with awbrm wheel 5! fixed on the spindle 8 between the bearings 34 and 35 tocomplete the rotary drive transmission.

The elongated headstock l is mounted on the table 6 for pivotaladjustment'about a vertical axis to permit either cylindrical or tapergrindassaeoo ing. More particularly, a tubular pivot sleeve 52 is fixedin the bottom of the housing 28, and is swiveled in a sleeve 58 in thetable 8. Pivotal adjustment of the headstock I may be effected by anysuitable means operable by a hand knob 54 at the front of the table 8,and the headstock is adapted to be clamped in position of adjustment bysuitable gibs 55 and 58 slidably overlying the extreme ends.

Fluid under pressure is adapted to be supplied reversibly to the motor48 through lines 51 and 58. To connect these lines to the motor withoutnecessitating the use of a perishable flexible hose, a manifold plate 58(see Figs. 6 and '7) is bolted to the left end of the base section 2below the table 8. The plate 58 is formed with three parallel bores 68opening therethrough longitudinally of the base section I to a recess 6|normally closed by a cover 62, and with three passages 88 peripherallyintersecting the bores. Two of the passages 83 are connectedrespectively to the lines 51 and 58 and the third is connected to adrain line 84. Anchored at their outer ends with a fluid tight seal tothe manifold block 58, in communication respectively with the bores 88,are

' three parallel tubes 85 which are plugged or closed at their innerends and. which extend freely through three parallel bores 88 openinglongitudinally through an elongated manifold block 81 on the undersideof the table 8.

Each of the tubes 65 is secured to the manifold plate 58 bya bolt 68extending through the associated bore 88 into internally threadedengagement with the tube and accessible in the recess 6!. The bolt 88 istubular and closed at the head end so as to constitute in effect anextension of the tube 65. and is formed with a plurality of radial ports88 open to the associated passage 463. The bore 88 in the manifold block61 is of a larger diameter than the tube 85 to provide a peripheralfluid space. Plain bushings 18 are fixed in the bore 88 adjacent theouter ends and have a close sliding fit with the tube 85 to provide aguide and a hydraulic seal. Suitable square wire snap rings 18a areinserted into internal grooves 18b in the bore 88 in position to engagethe outer ends of the bushings I8 and thereby anchor the latter againstthe high fluid pressure in the bore between the bushings. Additionalperipheral seals 1| are provided in the ends of the bore 88 in axiallyspaced relation to the bushings l8, and coact with the latter to definesmall intermediate annular spaces or chambers I2 adapted to collect anyoutwardly leaking fluid. The tube 85 is formed with radial ports 18which open from the interior thereof to the associated bore 66.

The various chambers 11 at the ends of the bores 88 are connectedthrough passages 14 in the manifold block 81 to one of the bores 88 incommunication with the drain line 64 so as to provide an outlet for theleakage of fluid. The other two bores 68 are in communication withpassages 15 opening through the block 81, the pivot sleeve 52 and thehousing 28, respectively. to opposite sides of the motor 43. It will beevident that the various tubes 85 and the block 81. by reason of theirtelescoping relationship, serve to connect the fluid lines 51 and 58 andthe drain line 84 to the carriage 6 in any position of reciprocation ofthe latter, and that the passages 15 in opening through the sleeve 52permit angular adjustment of the headstock without interfering with theconnection of the fluid lines 51 and 58 from the carriage to the motor48.

4 The new drive Translation of the table 8 is effected through a nut 18and alead screw 11 which are mounted for relative rotation,- and ofwhich one is fixed to the base section 2 and the other is movable withthe table. In the present instance, the 'nut 18 is supported in anormally fixed position in a sleeve 18 attached to the base section 2,and the screw 11 is supported for a rotary drive on the underside of thetable 8. One end of the screw TI is freely splined for relative axialadjustment in a sleeve 8i rotatably mounted in antifriction bearings 82conflned in a lug 83 on the side of the manifold block 81. Th sleeve 8|is operatively connected for rotation in timed relation to the workspindle 8. In the present instance, the drive connection includes a gear84 fixed on the inner end of the spindle 8 within the gear compartment88 of the headstock housing 28. The gear 84 is connected throughsuitable change gears 85 to a shaft 86 journaled in the wall 3!. Thechange gears 85 are adiustably and removably mounted on a quadrant 81pivoted on the shaft 86 and adapted to be clamped to the wall 8i inposition of adjustment by means of a bolt 88. Bevel gears 88 serve toconnect the shaft 88 to a vertical shaft 88 extending downwardlycoaxially through the pivot sleeve 52 and supported therein by suitableantifriction bearings 8|. The lower end of the shaft 88 is connectedthrough bevel gears 82 to the sleeve 8|, thereby completing the drive tothe lead screw 11.

The bottom of the gear compartment 88 constitutes a reservoir adapted tocontain a lubricant for the gearing therein. An oil pump 83 is mountedin the bottom of the compartment 88, and is driven by a cam 84 on thespindle 8. The pump 83 has an intake.- 85 below the oil level, and anoutlet line 88 discharging in the top of the compartment above thegearing.

The right end of the lead-screw TI is adjustably anchored in a fixedaxial position relative to the table 8. As herein shown, the right endshaft extension of the lead screw ii' extends slidably and rotatablythrough an elongated bearing sleeve 81 which is secured for axialadjustment in 9. lug 88 on the underside of the table 8. A backlashcompensating device 88 is mounted on the sleeve 81, and takes theendthrust of the lead screw 11.

Hydraulic operating system Fluid under pressure is adapted to besupplied by a variable delivery pump 483 having a discharge line 484 andan intake line 485 opening from a sump 488 within the base i. The pump483 may be of any suitable character, and preferably is of the orificepressure controlled type disclosed in Patent No. 2,299,234, issuedOctober 20, 1942, to Ira J. Snader and Max A. Mathys. More particularly,the pump 483 has a control line 481 which, as hereinafter described, isadapted to be connected by a valve 488 either to the exhaust side of thehydraulic system for utilization of a pressure built, up by a flowrestriction to cause the delivery of fluid in variable amounts asrequired and at a. predetermined substantially constant pressure withoutthe use of relief valves, or to the pressure discharge line 484 tosubstantially stop fluid delivery except as required to maintain saidpressure. The pump 483 may be driven by any suitable means, such as anelectric motor 8 connected thereto through a drive coupling 488, andcontrolled by start and stop buttons 4 and a master stop button 2 forthe entire machine on the front of the machine base i. To prevent thetransmission of vibration, the pump 603 and the motor s l are mounted ona base M3 resiliently supported as by rubber on the floor adjacent thebase i.

The pressure line tilt opens to a main hydraulic control panel sit onthe front of the base section 2. The hydraulic panel is sectionallyconstructed of castings and grooved plates housing the various controlvalves and defining the connecting passages in a compact arrangement.

A suitable direction and stop valve 5i! is operable to connect thepressure line 4M selectively to either of the lines 57 and 58 leading tothe motor 63 for driving the table 6 and the work spindle 8 andsimultaneously to connect the other of said motor lines to an exhaustline sis discharging to the sump tilt. I

In its preferred form, the valve ill comprises a tubular bushing tiefixed in a bore 620 in the panel tit, and having formed therein inlongitudinally spaced relation two pressure ports 42! and are of whichthe port :32! is connected to the line see, two motor supply ports M3and 624 between the pressure ports and connected respectively to thelines 5i and 58, and a central exhaust port 325 between the supply portsand connected to the exhaust line M8. A valve piston 26 of the spooltype is reciprocable in the bushing tit, and is formed with threelongitudinally spaced peripheral grooves or recesses 21, 428 and M9. Thecentral recess see is always open to the exhaust port are, and the endrecesses iii and 629 are interconnected through an axial bore 330 in thepiston 426 and are always open to the pressure ports iii and are. Itwill be evident that in one end position of the valve piston sit, the

lines 5'! and 58 will be connected respectively I to the pressure andexhaust lines tilt and iii! to operate the motor $3 in one direction,and in the other end position, the connections will be reversed tooperate the motor in the opposite direction. In the central or neutralposition, both lines El and 58 will be disconnected from the pressureline see and connected to the exhaust line its.

Suitable flow restriction means is interposed in the exhaust line M8 tocontrol the rate of drive by the motor as in either direction. In thepresent instance, this means consists of three adjustable restrictionorifice valves 43!, 432 and are located respectively in three parallelbranch lines see, 835 and $36, and adapted for selective connection inthe exhaust line M8 by a three position valve sew. These orifice valvesare independently adjustable from the front of the panel Me. In thepresent instance, the orifice valve 432 in the intermediate branch line435 is adjusted to provide a relatively large flow area adapted toeffect a rapid traverse, and the other orifice valves t3! and are areadjusted to provide relatively small fiow areas adapted to eflect slowdrive speeds or feeds.

The orifice selection valve til comprises a bushing sleeve s38 fixed ina bore stem the panel tit. Four longitudinally spaced ports 340, Mi, M2and M3 are formed in the sleeve 438 and open respectively to the linese35, see, are and M8. A valve piston M4 is reciprocable in the sleeve43B, and is formed with two longitudinally spaced sets of ports 5 and 6interconnected by an axial bore Ml. The arrangement is such that theports Mi and 448 are connected to institute rapid traverse when thepiston did is in central position, the ports II and M5 are connected toinetitute a slow feed when the piston is in one end position, and theports 2 and see are connected to institute a second slow' feed whenthepiston is in the other end'position.

The operation of the valves m and lei is under the control of aplurality of pilot valves consisting of a start and stop valve its,direction control valves 9 and 450, and speed control valves 4M and452.These pilot valves are located in a panel 5, and are included in pilotcontrol circuits under a relatively low operating pressure. v

Fluid is supplied from the main pressure line 606 to a pilot pressureline ass under the control of an automatic regulating valve ass, Thisvalve comprises a bore 455 opening centrally to a high pressure chamber458 connected to the line are, and at opposite ends respectively to alow pressure chamber Q51 connected to the line set and an exhaustchamber $58 connected to an auxiliary exhaust line 459 leading to thesump 40s. A plunger 46!! extends slidably through the bore 655, and isurged endwise against the pressure in the chamber '45? by a compressionspring tti seated against an adjusting screw sec in the exhaust chamber358. The plunger 56b is formed with a longitudinal bore 463 open to thelow pressure chamber 451, and adapted for communicationwith the chamber456 or the chamber Q53. When the pressure in the chamber s51 is too low,replenishing fluid will be supplied from the chamber E56 through thebore 463. When the pres sure is at the desired value determined by thespring 86!, the bore 663 will be closed to cut off the flow of fluid. Inthe event of high pressure leakage, the resulting excess pressure willbe bypassed to the exhaust chamber see. As a result, a balancedrelatively low constant pressure is substantially maintained in the line463 at all times.

The direction valve all is movable into stop position by two centeringplungers or collars 4% which are freely reciprocable in cylinders ate atopposite ends of the bore 20 for engagement with opposite ends of thevalve piston are. The outer ends or the cylinders 665 are open to a line6% adapted for connection by the pilot valve see eitier to the pressureline 653 or the exhaust line d5 The start and stop pilot valve 448comprises a valve bore s61 formed in and opening to the top oi the panelMB. A difierential valve plunger 56% is reciprocable in the bore 65?,and has an actuating stem 469 projecting outwardly for engagement by astop dog Mil adjustably mounted on the table 8. The bore s61 hassuitable port connections with the lines are and see, and is always openat the small end of the plunger its to the pressure line $53. The bored6? is also open at the large end of the plunger $69 to a line 6'adapted to be connected by a hand valve 612 either to the pressure lineset or the exhaust line 59. The hand valve M2 comprises a differentialcylinder 613 connected at the large and small ends respectively to thelines 4% and 59, and having suitable port connections in one side withthe lines 453 and d'li. A difierential valve piston 61% is reciprocablein the cylinder die by a hand lever 415. I

To institute operation, the valve piston did is moved into position toconnect the lines are and all. Thereupon, the valve plunger Q66 iselevated by differential pressure, and connects the lines 459 and 486 torelease the direction valve ill for adjustment into either end position.Upon lowering the pler see either by dog 418 or through actuation of thehand valve 412 to exhaust the line 411, pressure fluid is supplied tothe line 488 to center the direction valve 411 and to move or hold thehand valve 412 in stop position.

The direction valve 411 is reversible by two pins or plungers 418adapted to act against the opposite ends ofthe valve piston reversingplungers 418 is reciprocable in a cylinder 411 connected to a fluidsupply line 418, and extends axially through the adjacent centeringcollar 484. The other plunger 418 is reciprocable in a cylinder 418formed in the other centering collar 484, and connected through aperipheral port 488 in the latter to a fluid supply line 481. The lines418 and 481 are adapted to be connected through a rotary hand valve 482to two lines 483 and 484 controlled by the direction pilot valves 448and 458. The valve 482 is adjustable to reverse these connections forthe grinding of left hand threads so that the spindle drive willproperly conform to the lead screw rotation as controlled by the changegearing 85.

The pilot valves 448 and 458 respectively comprise two vertical bores485 and 488 formed in and opening to the top of the panel 415, and twospool valve plungers 481 and 488 reciprocabie therein and havin axialstems 488 and 488 projecting therefrom for selective engagement by dogs481 and 482 adjustably mounted on the table 8. The pressure line 453opens to the upper ends of the bores 485 and 488, and the pressure fluidtherefrom acts against the relatively small upper piston areas of theplungers 481 and 488. The bores 485 and 488 also have port connectionswith the'exhaust line 458 and respectively with the lines 484 and 483.The latter also open respectively to the lower ends of the bores 485 and485 to provide cross connections so that the pilot valves 448 and 458will reset each other alternately in operative position for respectivecoaction with the dogs 481 and 482.

The port connections are such that when the plunger 488 is depressed,the cross line 484 will be connected to the pressure line 453. therebycausing upward movement of the plunger 488 to connect the other crossline 483 to the exhaust line 458. As a result, the plunger 488 is lockedin depressed position, the plunger 488 is held in elevated position, andone directional pin 418 is actuated to move the direction valve 411 intoposition to institute carriage movement to the left. Conversely, whenthe plunger 488 is depressed, the lines 483 and 484 are connectedrespectively to the pressure and exhaust lines 453 and 458 to reversethe valve 4l1 and institute carriage movement to the right. Adjustmentof the hand valve 482 for grinding left hand threads will reverse themotor 43 and hence the rotation of the work spindle B in relation to thepilot valve control, but the directional control of the table 8 is leftunchanged by suitable changes in the gearing 85 in the lead screw drive.

The direction pilotvalves 448 and 458 may be reversed at any timeindependently of the dogs 481 and 482 by means of a hand valve 483. Tothis end, two lifting pistons 484 and 485 are mounted in cylinders 483and 481 at the lower ends of the bores 485 and 488, and normallyconstitute stops for the plungers 481 and 488. However, either of thesepistons 488 and 481 ma: be actuated hydraulically to elevate theassociated pilot plunger into operative position. The hand valve 483comprises a bore 488 having port connections with the pressure andexhaust lines 453 428. One of the' 8 and 458 and with two lines 488 and588 opening respectively to the lower ends of the lifting cylinders 488and 481. A valve piston 581 of the spool type is normally held by springmeans 582 in central position to connect both of the lines 488 and 588to the exhaust line 458. Movement of the valve piston 581 into oppositeend positions serves to connect the lines 488 and 588 repsectively andreversibly to the lines 453 and 458 to supply pressure fluid selectivelyto one or the other of the cylinders m and m.

The oriflce selection valve 431 is controlled by the rapid traversepilot valve 452 and e feed pilot valve 451 in conjunction with the dction pilot valves 448 and 458.

Two centering collars or pistons 583 and,584 are reciprocable incylinders 585 and 588 at oppositeends of the bore 438 for engagementsimultaneously with opposite ends of the valve piston 444. The outerends of the cylinders 585 and 588 are open in parallel to a line 581adapted for connection by the rapid traverse valve 452 either to thepressure line 453 or the exhaust line 458. The valve 452 in turn iscontrolled by the feed valve 451. These valves 451 and 452 respectivelycomprise vertical bores 588 and 588 formed in and opening to the top ofthe panel 415, and spool type valve plungers 518 and 511 reciprocabletherein and having stems 512 and 513 projecting therefrom for selectiveactuation by dogs 514 and 515 adjustably mounted on the table 8. Bothbores 588 and 588 are open at the upper end above the small piston areasof the plungers 518 and 511 to the pressure line 453 and have portconnections with the exhaust line 458. The bore 588 also has a portconnection with the line 581 which has a. cross connection with thelower end of the bore 588 below the large piston area of the plunger518. Likewise the bore 588 has a port connection with a cross line 514aopening to the lower end of the bore 588 below the large piston area ofthe plunger 5| 1.

The port connections are such that when the plunger 511 is depressedpressure fluid is supplied from the line 453 to the line 581 to elevatethe plunger 518 and center the valve 431. At the same time, the plunger518 connects the cross line 5140 to the exhaust line 458 to lock thevalve 513 in its lower position. Fluid from the motor 43 is nowexhausted through the rapid traverse orifice 432. when the feed plunger518 is depressed, pressure fluid is supplied from the line 453 to thecross line 514a to elevate the plunger 511 which thereupon connects theline 581 to the exhaust line 458 to relieve the cylinders 585 and 588and the lower end of the bore 588,

when the feed plunger 518 is depressed, the valve 431 is selectivelyadjustable automatically into opposite end positions as determined bythe direction of carriage travel under the control of the directionpilot valves 448 and 458. Thus, two adjusting pistons 515a and 518 arereciprocable in cylinders M1 and 518 at opposite ends of the valve bore438 and extend slidably through the centering pistons 583 and 584 forengagement respectively with opposite. ends of the valve piston 444. Theouter ends of the cylinders 511 and 518 are connected respectively tothe lines 483 and 484. It will be evident that when the plunger 488 isdepressed to institute carriage movement to the right, pressure fluid issupplied to the cylinder 51! to connect the feed orifice 433 in theexhaust line 458. Alternatively, when the plunger 481 is depressed toinstitute carriage movement to the left, the feed orifice 431 isconnected in 9 the exhaust line 463.. The orifice valves 43! and 433 maybe relatively adjusted to obtain the same or different rates of drive inopposite directions of carriage travel.

The table dogs may be selected and mounted to obtain difl'erent cyclesof operation. The position of the reversing dogs 4M and 492 determinesthe location and extent of the range of table reciprocation. The stopdog 4'lllis of the pivotal gravity type and adapted to depress the stem469 only upon movement of the table 6 in one direction. To stop thetable in the opposite direction, it is merely necessary to reverse thedog 4'") on the pivotal mounting. After depressing the stem 469, the dog416 will swing past the latter to permit institution of the next cycle.In the arrangement as shown, if the direction dog 4!" is adapted toengage the stem 489 before the dog 4'! can engage the stem 469, thetable reciprocation will be continuous. Conversely, if the dog 410 isadapted to engage the stem 469 before the direction dog 4!" can engagethe stem 489, the table 6 will come to a stop at the end of theright-hand movement.

Each of the speed control dogs M and H5 is also operable only uponmovement of the table in one direction. As shown, the feed dog 5% isfreely pivotal to the left and is, therefore, adapted to drag freelyover the stem 5l2 upon movement of the table to the right and to depressthe stem only upon movement to the left. To institute feed during tablemovement to the right, it is merely necessary to reverse the dog 514 onthe pivotal mounting, The rapid traverse dog M5 is adapted to depressthe stem 5| 3 upon movement of the table to the right but is ineffectivein the opposite direction of movement. It will be understood that anydesired number of dogs EM and 5l5 efiective in either direction may beprovided depending on the particular series of rapid traverse and feedmovements to be obtained.

The pump control valve 468 is operable synchronously with the directionvalve 4" under the control of the start and stop pilot valve 448. Thisvalve 406 comprises a bore 5l9 open at one end to the adjacent cylinder465 and at the other end to the exhaust line 459, and having portconnections with the pressure line 453, the pump control line 401 and aline 520 branching from the exhaust line 4H8 ahead of the orificeselection valve 431. 52! is reciprocable in the bore 5l9. When pressurefluid is supplied to the cylinders 465 to center the valve 4|! in stopposition, it also acts on the large piston area of the assembly Hi toconnect the motor control line 401 to the high pressure line 404 andthereby reduces the delivery of the pump to maintain a low pilotpressure in the system. When the adjacent cylinder 465 is exhausted,pressure fluid from the line 453 acts on the small piston area of theplunger 52l to connect the control line 461 to the'oriflce pressure line520. The pressure set up in the exhaust line M8 by the selected orificevalve now controls the pump 403 to obtain a variable delivery asrequired at a constant predetermined pressure.

It will be seen that the main valves 4H and 431 and the various pilotvalves 448, 449, 450, 45| and 452 are controlled and operated by therelatively low pilot pressure. As a result, the

A differential valve piston assembly can be made relatively lightwithout the likelihood of leakage.

' Operation The operation of the machine will be apparent from theforegoing description, and briefly summarized is as follows:

The work to be ground is attached to the work spindle 8. Then, the valve531 is adjusted to obtain the desired direction of spindle rotation, andsuitable change gears 85 are used to correlate the translation of thetable 6 both in rate and direction to the spindle rotation so as todescribe the desired thread lead.

The switch 4 is actuated to start the motor em, and the lever 415 isactuated to institute operation of the table 6 and the spindle 8. Thetable 5 will now be translated automatically through a predeterminedcycle which may comprise any desired program of rapid traverse and feedmovements. At any point in the cycle, the direction may be reversed byactuating the hand valve 493. The rapid traverse rate is determined bythe exhaust orifice 432, and the feed rates in opposite directions arecontrolled respectively by the orifices 43! and 433. These orifices areindependently adjustable. The reciprocation of the table 5 may becontinuous or interrupted depending on the location of the stop dog 410.The

operation may be discontinued at any time by actuating the hand lever415.

The hydraulic operating mechanism for machine tools including more thanone hydraulic motor is covered in my copending divisional applicationentitled "Hydraulic transmission for machine tools," Serial No. 787,869,filed November 25, 1947.

I claim as my invention:

1. A hydraulic operating mechanism for a re-' versible machine elementcomprising, in combination, areversible motor having inlet and outletmotor lines for driving said element at selected feed and rapid traverserates of movement in both directions, an exhaust line, a fluid pressuresupply line, a direction control valve reversibly adjustable intoopposite limit positions to connect said motor lines respectively andreversibly to said pressure and exhaust lines and movable into anintermediate step position to interconnect said motor lines and saidexhaust line, three independently adjustable flow restriction orificesarranged in parallel, an orifice selection valve reversibly adjustableinto opposite limit positions to connect one or the other of two of saidorifices relatively high pump pressure can be con-fined respectively insaid exhaust line, and adjustable into intermediate position to connectthe third orifice in said exhaust line, and means automatically operableupon movement of said element into different predetermined positions toadjust said selection valve respectively to connect one of said orificesfor control of the feed rate of said element in one direction ofmovement, another of said orifices for control of said feed rate in theother direction of movement, and the third of said orifices for controlof the rapid traverse rate of said element in either direction ofmovement.

2. A hydraulic operating mechanism for a reversible machine element, areversible motor having inlet and outlet motor lines for driving saidelement, an exhaust line, a pressure fluid supply line, a directioncontrol valve reversibly adjustable into opposite limit positions toconnect said motor lines respectively and reversibly to said pressureand exhaust lines and movable into an 11' intermediate stop position todisconnect said mo-' tor lines from said pressure line, threeindependently adjustable flow restriction orifices arranged in parallel,an orifice selection valve reversibly adjustable into opposite limitpositions to concontrolling the supply of fiuid under pressure selectively to opposite sides of said motor to causesaid motor to operatein one direction or the other, hydraulic actuator means for reversingsaid valve means and including two control lines adapted alternately toreceive fluid under pressure, pilot valve means operable by said elementfor controlling said hydraulic actuator means and having two controllines, and valve means for connecting said last mentioned control linesto said first mentioned control lines and being adjustable to reversethe connections of said lines whereby to reverse the direction controlby said pilot valve means of said direction valve means.

4. A hydraulic operating mechanism for a reversible translatory machineelement and a reversible rotary machine element carried by saidtranslatory element comprising, in combination, a reversible hydraulicmotor connected to drive said rotary element and connected through a re-12 nected selectively in said exhaust line, a selection valve movableinto opposed positions to connect one or the other of said orificesrespectively insaid exhaust line, hydraulic actuator means for saidselection valve and including a set of two control lines adapted toreceive fluid selectively to adjust said selection valve respectivelyinto said opposed positions, pilot valve means automatically operable bysaid translatory member for controlling said two actuator means andincluding two control lines adapted for connection respectively inparallel to the lines of said two sets of control lines, and reversiblevalve means respectively interconnecting the. control lines of saidpilot valve means to said two sets of control lines of said actuatormeans.

6. A hydraulic operating mechanism for a reversible machine elementcomprising, in combination, a reversible motor having inlet and outletmotor lines for driving said element, an exhaust line, afiuid pressuresupply line, a direction control valve reversibly adjustable intoopposite limit positions to connect said motor lines respecversiblemechanical transmission to reciprocate said translatory element, asource of fiuid under pressure.- an exhaust line, reversible directionvalve means adjustable into opposed positions to connect said source andsaid exhaust line respectively and reversibly to opposite sides of saidmotor, hydraulic actuator means for said direction valve means andincluding two control lines adapted to receive fluid selectively toadjust said direction valve means respectively into said oppositions,pilot valve means automatically operable by said translatory member forcontrolling said actuator means and including two control lines adaptedfor connection respectively to said first mentioned control lines tosupply fiuid under pressure alternately thereto, and reversible valvemeans respectively interconnecting the control lines of said pilot valvemeans to the control lines of said actuator means.

5. A hydraulic operating mechanism for a reversible translatory machineelement and a reversible rotary machine element carried by saidtranslatory element comprising, in combination, a reversible hydraulicmotor connected to drive said rotary element and connected through areversible mechanical transmission to reciprocate said translatoryelement. a source of fluid under pressure, an exhaust line, reversibledirection valve means adjustable into opposed positions to connect saidsource and said exhaust line respectively and reversibly to oppositesides of said motor, hydraulic actuator means for said direction valvemeans and including a set of two control lines adapted to receive fiuidselectively to adjust said direction valve means respectively into saidopposed positions, two independently adjustable restriction orificesadapted to be contively and reversibly to said pressure and exhaustlines and movable into an intermediate stop position, threeindependently adjustable fiow restriction orifices arranged in parallel,a reciprocable orifice selection valve reversibly adjustable intoopposite end positions to connect one or the other of two or saidorifices respectively into said exhaust line and adjustable into anintermediate position to connect a third orifice in said exhaust line,pilot valve means automatically operable by said element to adjust saidselection valve selectively into said opposite limit positions, andpilot valve means automatically operable by said element to adjust saidselection valve out of either limit position into said intermediateposition.

7. A hydraulic operating mechanism for a reversible machine elementcomprising, in combination, a reversible motor having inlet and outletmotor lines for driving said element, an exhaust line, a fiuid pressuresupply line, a directional control valve reversibly adjustable intoopposite limit positions to connect said motor lines respectively andreversibly to said pressure and exhaust lines and movable into anintermediate stop position, three independently adjustable fiowrestriction orifices arranged in parallel, a reciprocable orificeselection valve having a valve member reversibly adjustable intoopposite limit positions to connect one or the other of two or saidorifices respectively in said exhaust line and adjustable intointermediate position to' connect the third orifice in said exhaustline, two centering collars arranged for engagement re spectively withopposite ends or said valve memher and movable simultaneously into oneposition to center said valve member or into another position to releasesaid valve member for movement into either of said limit positions,pilot valve means automatically operable by said ma chine element forcontrolling said centering collars, two reversing plungers actingrespectively against opposite ends of said valve member, and pilot valvemeans automatically operable by said machine element to direct fiuidunder pressure selectively to actuate one orthe other 0! said plungerswhereby to reverse said selection valve.

8. A hydraulic operating mechanism for a reversible machine elementcomprising, in combination, a reversible motor having inlet and outletmotor lines for driving said element, an exhaust line, a fluid pressuresupply line, a direction control valve reversibly adjustable into op- 13posite limit positions to connect said motor lines respectively andreversibly to said pressure and exhaust lines and movable into anintermediate stop position, three independently adjustable fiowrestriction orifices arranged in parallel, a reciprocable orificeselection valve having a valve member reversibly adjustable intoopposite limit-positions to connect one or theother of two of saidorifices respectively in said exhaust line and adjustable intointermediate position to connect the third orifice in said exhaustline.two centering collars arranged for engagement respectively with oppositeends of said valve member and movable simultaneously into one positionto center said valve member or into another position to release saidvalve member for movement into either of said limit positions, pilotvalve means automatically operable by said machine element forcontrolling said centering collars, two reversing plungers actingrespectively against opposite ends of said valve member, pilot valvemeans automatically operable by said machine element to direct fluidunder pressure selectively to actuate one or the other of said plungerswhereby to reverse said selection valve and being simultaneouslyoperable to reverse said direction valve means, and valve means in theconnections between said last mentioned pilot valve means on one handand said direction valve means and selection valve on the other hand ad-1 lustable to reverse said connections.

9. A hydraulic operating mechanism for a reversible machine element, areversible motor having inlet and outlet pressure lines for driving saidelement, an exhaust line, a pressure fluid supply line. a directioncontrol valve reversibly adjustable into opposite positions to connectsaid motor lines respectively and reversibly to said pressure andexhaust lines, hydraulic actuator means for reversing said controlvalve, pilot valve means having control lines connected to said actuatormeans and being automatically operable by said machine element toconnect said control lines respectively and reversibly to said pressureand exhaust lines whereby to reverse said control valve, hydraulicactuator means for said pilot valve means, and a manually operable valvefor controlling the connection 01' said last mentioned actuator means tosaid pressure and exhaust lines and being adiustable independently ofsaid machine element to efiect actuation of said pilot valve means toreverse the connections oi said control lines to said first mentionedactuator means whereby to eiiect reversal of said motor ing normallybiased into one of its two positions of adjustment.

10. A hydraulic operating mechanism for a reversible machine element, areversible motor having inlet and outlet lines for driving said element,an exhaust line, a pressure fluid supply line, a variable displacementpump connected to or to said exhaust line to release said control atwill independently 0! operation o!v said pilot 5;

valvemeansbysaidelemenasaidlastvalvebevalve for adjustment into saidopposed positions, said pump having a control line and being adjustablein displacement in response to pressure variations in said control line,and valve means automatically adjustable to connect said control line tosaid pressure line upon connectionv of said last mentioned inlet line tosaid pressure line and to connect said control line to said exhaust lineupon connection 01 said last mentioned inlet line to said exhaust line.

IRA J. SNADER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Date Number Name 410,180 Ongley Sept. 3, 1889-498507 Clark May 30, 1893 560,230 Powers May 19, 1896 1,338,379 LeachApr. 27. 1920 1,363,333 Lower Dec. 28, 1920 1,779,586 Chalker Oct. 28,1930 1,805,056 Taylor May 12, 1931 1,943,061 Douglas Jan. 9, 19341,976,122 Haas Oct. 9, 1934 2,000,553 Alden May 7, 1935 2,000,805 Westet a1. May 7, 1935 2,067,492 Kingsbury Jan. 12, 1937 2,157,240 Keel May9, 1939 2,157,707 Keel May 9, 1939 2,196,231 Ridgway Apr. 9, 1940FOREIGN PATENTS Number Country Date 410,728 Great Britain Aug. 10, 1932

